Leinster will be playing at the RDS for the first time tomorrow in the Celtic League against Cardiff.
The game, which kicks off at 5.30pm, will act as preparation for the RDS becoming the venue for Heineken Cup games.
Around 14,000 are expected for the match so the roads and public transport around the RDS will be congested.
Also at the RDS is STAMPA, the three-day philatelic exhibition this weekend, and organisers expect over 2,000 people to attend.
Racing this weekend in Cork and Naas will also cause traffic delays - in Cork on both Saturday and Sunday afternoons, and Naas on Sunday afternoon.
Met Éireann says the weather over the weekend will continue quite balmy with temperatures reaching the upper teens. Saturday night will be mild, breezy and mostly dry.
Sunday will begin dry, with some bright spells possible during the morning, but it will become more overcast through the day, and there may be some patchy light rain by evening.